The myotendinous junction (MTJ) is a highly specialized region of the locomotor apparatus. Here, we investigated the ultrastructural and molecular effects in the MTJ region after static stretching prior to the ladder-based resistance training. Thirty-two male, 60-day old Wistar rats were divided into four groups: Sedentary, Resistance Training, Stretching, and Stretching-Resistance Training. The gastrocnemius muscle was processed for transmission electron microscopy techniques and Western blot assay. We observed that the static stretching prior to the ladder-based resistance training increased the MTJ components, the fibroblast growth factor (FGF)-2 and FGF-6 protein expression. Also, we demonstrated the lower transforming growth factor expression and no difference in the lysyl oxidase expression after combined training. The MTJ alterations in response to combined training demonstrate adaptive mechanisms which can be used for the prescription or development of methods to reduce or prevent injuries in humans and promote the myotendinous interface benefit.

The Recruitment Innovation Center (RIC) has created a toolkit of novel strategies to engage potential participants in response to recruitment and retention challenges associated with COVID-19 studies. The toolkit contains pragmatic, generalizable resources to help research teams increase awareness of clinical trials and opportunities to participate; produce culturally sensitive and engaging recruitment materials; improve consent and return of results processes; and enhance recruitment of individuals from populations disproportionately impacted by COVID-19. This resource, the “RIC COVID-19 Recruitment and Retention Toolkit,” is available free online. We describe the toolkit and the community feedback used to author and curate this resource.

A previously healthy 15-year-old teenage boy was admitted for fever and heart failure. Myocarditis was suspected, and endomyocardial biopsy revealed giant cell myocarditis. Immunosuppressive treatment was initiated, with excellent response. A plausible link to previous leptospirosis was identified. At 18-month follow-up, left ventricular function is normal. Only one other reported case of paediatric giant cell myocarditis had such a favourable outcome.

Protein quality has an important role in increasing satiety. Evidence suggests that whey protein (WP) provides satiety via gastrointestinal hormone secretion. Hydrolysed collagen supplementation can also stimulate the production of incretins and influence satiety and food intake. Thus, we sought to compare the effect of acute supplementation of WP or hydrolysed collagen on post-intervention appetite and energy consumption. This was a randomised, double-blind, crossover pilot study with ten healthy adult women (22·4 years/old) who were submitted to acute intake (single dose) of a beverage containing WP (40 g of concentrated WP) or hydrolysed collagen (40 g). Subjective appetite ratings (feelings of hunger, desire to eat and full stomach) were measured using the Visual Analog Scale (VAS), energy intake was quantified by ad libitum cheese bread consumption 2 hours after supplementation and blood was collected for leptin and glucose determination. There was no difference between treatment groups in the perception of hunger (P = 0·983), desire to eat (P = 0·326), full stomach feeling (P = 0·567) or food consumption (P = 0·168). Leptin concentrations at 60 min post supplementation were higher when subjects received hydrolysed collagen (P = 0·006). Acute supplementation with hydrolysed collagen increased leptin levels in comparison with WP, but had no effect on appetite measured by feelings of hunger, desire to eat, full stomach feeling (VAS) or energy consumption.

The myotendinous junction (MTJ) is the interface between muscle and tendon, and it is the main area of force transmission of the locomotor apparatus. Dystrophic processes promote pathological injury which affects the skeletal muscle and can influence the morphology of the MTJ. This study aimed to investigate the adaptations in MTJ morphology of mdx mice in the tibialis anterior muscle. Male mice (n = 24) were divided into Control—C57bl/10 and mdx—C57bl/10mdx (Duchenne muscular dystrophy experimental model). In the mdx group, centralized nuclei with a large area and greater deposition of type III collagen (fibrosis) were observed. Also, shorter sarcomeres and sarcoplasmatic projections of MTJ were observed. We concluded that the adaptations in mdx mice demonstrated extensive impairment in the MTJ region with reduced ultrastructures.

Camelid pastoralism, agriculture, sedentism, surplus production, increasing cultural complexity, and interregional interaction during northern Chile's Late Formative period (AD 100–400) are seen in the flow of goods and people over expanses of desert. Consolidating evidence of material culture from these interactions with a bioarchaeological dimension allows us to provide details about individual lives and patterns in the Late Formative more generally. Here, we integrate a variety of skeletal, chemical, and archaeological data to explore the life and death of a small child (Calate-3N.7). By taking a multiscalar approach, we present a narrative that considers not only the varied materiality that accompanies this child but also what the child's life experience was and how this reflects and shapes our understanding of the Late Formative period in northern Chile. This evidence hints at the profound mobility of their youth. The complex mortuary context reflects numerous interactions and long-distance relationships. Ultimately, the evidence speaks to deep social relations between two coastal groups, the Atacameños and Tarapaqueños. Considering this suite of data, we can see a child whose life was spent moving through desert routes and perhaps also glimpse the construction of intercultural identity in the Formative period.

Static stretching provides benefits to the range of motion, modulates intramuscular connective tissue, and is incorporated into warm-up exercises. In this study, we present the effects in the motor endplate and belly muscle resulting from previous static stretching to climbing training. Twenty-four adult male Wistar rats were divided into four groups (n = 6 each): Sedentary (Sed), Climbing (Clb), Static stretching (Ss), and Static stretching prior to climbing (Ssc). The animals (Clb, Ss, and Ssc groups) were subjected to a training protocol 3×/week for 8 weeks, and the Ssc group was subjected to the Ss and Clb protocols in the same session. Samples from the animals were processed for immunostaining, histochemistry, and light microscopy. The Clb group presented a higher motor endplate; the Ss group presented no changes in the motor endplate; and the Ssc group demonstrated a higher compactness. We concluded that static stretching prior to the climbing protocol maintained the density of the motor endplate and increased the compactness of the neuromuscular junction structure. Also, there was a reduction in the myofibers’ diameter (Type I and IIa), an increase in myofibrillar densities (Type I and IIx, and total), and the reorganization of the myonuclei and the interstitium.

Obesity is characterized by excess adipose tissue and chronic inflammation and promotes extensive changes that can compromise skeletal muscles’ structural and functional integrity. Obesity can seriously impact the force transmission region between the muscle and the tendon, the myotendinous junction (MTJ). The present study aimed to investigate the plasticity of muscle fibers and MTJ regions in high-fat diet-induced obesity in rat tibialis anterior (TA) and soleus (SO) muscles. Wistar rats were divided into control and obese groups (induced by a high-fat diet). The samples of TA and SO muscles were prepared for histochemical and ultrastructural analysis (sarcomeres and MTJ projection). In the muscle fiber, similar adaptations were observed between the muscles of the smaller fiber (types I and IIa) in the obesity results. The MTJ region demonstrated different adaptations between the analyzed muscles. The TA–MTJ region has shorter ultrastructures, while in the SO–MTJ region, the ultrastructures were larger. We conclude that obesity induced by a high-fat diet promotes similar adaptation in the muscle fibers; however, in the MTJ region, the sarcoplasmatic projections and adjacent sarcomere demonstrate different adaptations according to distinct muscle phenotypes.